The aim of this project is to characterize schistosome surface molecules relevant to immunity, to analyze the genome of the parasite in relation to specific biologic properties of the organism and to clone important schistosome immunogens. A. Cloning and nucleotide sequencing of the Sm-97 vaccine antigen. Two clones expressing epitopes of the SM-97 vaccine immunogen were obtained from a lambda gt-11 expression library. One of these clones corresponding to 60% of the native molecule was sequenced and the protein deduced to be an alpha-helical coiled coil protein with a structure and amino acid sequence similar to that of paramyosin -- an invertebrate muscle protein. The identity of Sm-97 as paramyosin was confirmed by purifying from schistosomes by conventional chemical procedures and demonstrating identify with Sm-97 by Western blotting. B. Identification of a RFLP associated with drug resistance. A restriction fragment length polymorphism (RFLP) was identified in the DNA of schistosomes with experimentally induced resistance to the anti-parasitic drug hycanthone. This RFLP was absent in the susceptible parent line as well as in other susceptible strains.